#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

int main(void)
{
    int fd;
    int ret = 0;
    
    fd = open("test_file", O_RDONLY);
    if (-1 == fd) {
        printf("Error: open test_file failed!\r\n");
        close(fd);
        return -1;
    }
    printf("OK: open test_file sucessly!\r\n");
    close(fd);
    
    return ret;
}